Squeegee mount to independently adjust squeegee angle and pressure

ABSTRACT

A squeegee structure for a screen printing machine in which the squeegee is suspended at both ends by a lever having its pivotal axis coinciding with the edge of the squeegee blade which is in contact with the inner surface of the screen.

United States Patent 1191 Anselrode June 3, 1975 [54] SQUEEGEE MOUNT TO INDEPENDENTLY 2,202,799 5/1940 Jackson et al. 101/124 AD UST UEEGE G E AN 2,210,633 3/1940 Van der Rels 101/115 S? E L D 2,295,979 9/1942 Gordon 101/123 2,498,917 2/1950 Gattuso 101/124 [75] Inventor: Lodewijk Anselrode, St. Anthonis, 2,534,320 l2/I950 Taylor........ 101/169 UX Neth fl nd 2,814,987 12/1957 Foard...... 101/123 X 3.006.275 10/1961 Allen 101/157 Asmgneer Stork Amsterdam p aan, 3,109,365 11/1965 Karlyn 101/124 Amstelveen, Netherlands 3,139,823 7/1964 Landesman 101/124 Filed: 1 Feb. 1972 3.276536 10:9;6 Usko et al 101/115 X RElG ATENTS OR APPLICATIONS [211 App! 230330 2,006,887 1/1970 France 480,949 12/1969 Switzerland 101/120 [30] '7 Foreign Application Priority Data Mar. 16, 1971 Netherlands 7103481 Assistant Examiner-R. E. Suter 52 US. (:1. 101/119; 101/120; 101/123; Firm-Edmund Jaskiewicl 101/124 51 1n1.C1 1141115/42 ABSTRACT [58] Field of Search 101/119, 120, 115, 123, A squeegee structure for a screen printing machine in 101/124, 114, 116, 121, 157, 169 which the squeegee is suspended at both ends by a lever having its pivotal axis coinciding with the edge of [56] References Cited the squeegee blade which is in contact with the inner UNITED STATES PATENTS surfafie of the Screw 2,071,824 2/1937 Engerl 101/116 5 Claims, 2 Drawing Figures PATENTEDJUH 3 I975 SHEET PATEi-HEUJum 1975 885, 861

SHEET SQUEEGEE MOUNT TO INDEPENDENTLY ADJUST SQUEEGEE ANGLE AND PRESSURE BACKGROUND OF THE INVENTION My invention relates to a screen printing machine comprising a frame and movably provided therein at least one stencil with an adjustable squeegee, operative in a path along which the material to be printed is advanced while each squeegee consists of a strip with an edge which can be brought into contact with the associated stencil, and the strip is secured to supporting means which at its two ends is supported in the frame by an adjustable suspension device.

In such a commonly known device the printing paste is pressed, by means of the squeegee, through the perforations of the stencil. The quantity of paste pressed through the perforations is affected by the angle of the nip between the strip of the squeegee and the stencil inner surface, and by the force by which the edge of the strip presses against the stencil. The nip angle which can range from about to 90 gives rise to shearing forces because of the relative movement of squeegee strip and stencil during printing.

As a function of the flow characteristics and the viscosity of the printing paste, the width and thickness of the squeegee strip are so determined that the required quantity of printing paste is brought on and/or into the material to be printed.

In the screen printing machines so far known, there are restrictions in determining the nip angle and the compressive force of the squeegee strip since the suspension members and the supporting member of the squeegee strip only allow a particular adjustment of the nip angle and this adjustment is a function of the compressive force. This means that a particular nip angle applied to a squeegee to produce a certain compressive force will not produce the same compressive force when applied to another squeegee of different construction. As a consequence, since the bending stiffness of different squeegees is not always equal, in spite of the application of the same identical nip angle to squeegees of different structure, there is produced a different printing effect by each squeegee because of, the difference in compressive force. This is especially an inconvenience in printing absorbing materials, since the extent of penetration is strongly influenced by the value of the compressive force between the squeegee strip and the stencil.

SUMMARY OF THE INVENTION It is an object of my invention to provide a device in which the nip angle between the squeegee strip and the stencil can be adjusted at any desired value and entirely independent of the compressive force of the squeegee. For this purpose the suspension device allows a rotation of the squeegee around a pivot axis situated on an extension of a line passing along the edge of the squeegee strip contacting the screen. Due to this feature the axis of rotation of the squeegee strip will coincide, in the operative position of the squeegee with the line of contact between stencil and squeegee strip. The squeegee strip pivots as it were around its line of contact with the stencil, so that any arbitrary nip angle may be adjusted, unaffected by the compressive force. The adjustment of the two parameters: nip angle and compressive force can be effected independently of one an other.

For making the squeegee inoperative (e.g. when the printing process is interrupted) and for adjusting the compressive force each suspension device consists of a first lever the axis of rotation of which is ad justably supported on the frame of the machine. The adjustable support of the axis of rotation of the first lever is preferably in a second lever which allows an adjustment of the squeegee in a vertical direction perpendicular to the printing path.

DESCRIPTION OF A PREFERRED EMBODIMENT Other objects and advantages of the present invention will be apparent when taken in conjunction with the accompanying description and the following drawings, which are exemplary, wherein;

FIG. I is a side elevational view of that portion of the printing machine to which the present invention relates and showing the adjusting structure; and

FIG. 2 is an exploded view in perspective of the adjusting structure of FIG. I.

The construction of the device corresponds substantially with the embodiments described in US. Pat. No. 3,313,232 and in the copending applications Ser. Nos. lO8,394 now abandoned, 8l L787 now abandoned and SL043 now US. Pat. No. 3,7l8,086. The drawings show therefore only the structure to which my invention relates, i.e. the support and suspension of the squeegee. The aforementioned patents and patent application and the drawing relate to a so called cylindrical screen printing machine which is a printing device in which one or more thin-walled cylindrical stencils are employed. The invention is, however, not limited thereto since the screen structure can also advantageously be applied to a fiat bed printing machine.

In FIGS. 1 and 2 there is shown a part of the frame 1 of the machine and a stencil 2 rotatably mounted in the frame. In each stencil an adjustable squeegee 3 is provided. This stencil is operative in a path A along which the material to be printed (e.g. a web of fabric or loose sheets of paper) is advanced. Each squeegee comprises a supporting member 4 with a fitting 5 for a squeegee strip 6 proper. The member 4 is constructed in the usual way as a tube through which the printing paste is fed to the interior of the stencil 2. The supporting member 4 is hung at its two ends protruding from the stencil on adjustable suspension members 7 consisting of a lever 8, supported in the frame I. The lever 8 in this case constructed as a bell crank lever, has a pivotal axis 9 situated on the extension of a line along the edge 10 of the squeegee strip 6.

The pivotal axis 9 of the first lever 8 is supported in a second lever 11 allowing an adjustment in a vertical direction perpendicular to the printing path A. For that purpose the second lever 11 has a pivotal axis 12 on the frame I of the machine. The one end of the lever 11 carries the pivotal axis 9 of the first lever 8, while the other end via an operating rod 13 is connected with a fluid operating member 14, e.g. consisting of the usual pneumatic jack. The one end 15 of the first lever 8 carries the supporting member 4 of the squeegee 3, while the other end 16 cooperates with both an adjusting mechanism 17 and a graduated scale 18.

The mechanism 17 comprises a nut 19 connected with the end I6 of the bell crank lever 8 and cooperating with a threaded rod 20 which via an universal joint 21 and a bevel gearing 22 is connected with a hand wheel 23. By turning this hand wheel 23 the rod 20 is rotated to move the nut 19 along the threaded rod 20 to rotate the lever 8 around its pivotal axis 9 which coincides with the line 10 of contact. The pivoting lever 8 thus moves the squeegee support 4 downwardly but at the same time imparts a sideward or lateral movement to the support. The downward and lateral components of movement produce a pivoting movement of the entire support 3-6 about the pivot axis 9. As a result the nip angle a between the squeegee strip 6 and the inner surface of the stencil 2 is adjusted without any change in the compressive force of the squeegee strip. it is thus possible to adjust to any nip angle required or desired for a particular printing effect and to subsequently determine independently of the nip angle the compressive force of the squeegee strip via the lever 11, rod 13 and the operating member 14.

The invention renders it possible to adjust independently of each other the nip angle and the force by which the squeegee presses against the stencil, which allows more freedom in realizing exactly any desired printing effect. The invention can be applied both with rigid and rather soft squeegee strips such as applied in the screen printing technique.

It is understood that this invention is susceptible to modification in order to adapt it to different usages and conditions and, accordingly, it is desired to comprehend such modifications within the invention as may fall within the scope of the appended claims.

What I claim is:

1. In a screen printing machine, the combination of a frame, a squeegee supporting means comprising a tubular member positioned within a rotatable cylindrical stencil, said tubular member having both its ends protruding outwardly beyond both edges of the stencil, a squeegee secured to said supporting means and having an elongated edge for contacting the inner surface of said rotatable cylindrical stencil, and adjustable suspension means mounted on said frame connected to both ends of said squeegee supporting means and comprising at least one mounting member pivotable about an axis coextensive with said edge of the squeegee for tilting said squeegee and supporting means about said axis to vary the angle of nip between the squeegee and the screen without changing the compressive force of the squeegee.

2. In a screen printing machine, as claimed in claim 1 wherein said mounting member comprises a first lever pivotally mounted on a first pivot axis coincident with the said axis about which said squeegee is tilted, and means on said frame for adjustably supporting said first pivot axis.

3. In a screen printing machine as claimed in claim 2 wherein said adjustable suspension means comprises a second lever pivotally mounted on said frame to adjust said first pivot axis substantially perpendicular to a plane tangential to the stencil in the vicinity of the contact of the stencil by the squeegee.

4. In a screen printing machine as claimed in claim 3 wherein said first lever comprises a bell crank having first and second ends, said supporting means being connected to said first end, and an adjustable mechanism movable along a scale connected to the second end of said bell crank.

5. in a screen printing machine as claimed in claim 4 wherein said second lever comprises first and second ends, said first pivot axis being on the first end of said second lever, and fluid operating means connected to the second end of said second lever. 

1. In a screen printing machine, the combination of a frame, a squeegee supporting means comprising a tubular member positioned within a rotatable cylindrical stencil, said tubular member having both its ends protruding outwardly beyond both edges of the stencil, a squeegee secured to said supporting means and having an elongated edge for contacting the inner surface of said rotatable cylindrical stencil, and adjustable suspension means mounted on said frame connected to both ends of said squeegee supporting means and comprising at least one mounting member pivotable about an axis coextensive with said edge of the squeegee for tilting said squeegee and supporting means about said axis to vary the angle of nip between the squeegee and the screen without changing the compressive force of the squeegee.
 1. In a screen printing machine, the combination of a frame, a squeegee supporting means comprising a tubular member positioned within a rotatable cylindrical stencil, said tubular member having both its ends protruding outwardly beyond both edges of the stencil, a squeegee secured to said supporting means and having an elongated edge for contacting the inner surface of said rotatable cylindrical stencil, and adjustable suspension means mounted on said frame connected to both ends of said squeegee supporting means and comprising at least one mounting member pivotable about an axis coextensive with said edge of the squeegee for tilting said squeegee and supporting means about said axis to vary the angle of nip between the squeegee and the screen without changing the compressive force of the squeegee.
 2. In a screen printing machine, as claimed in claim 1 wherein said mounting member comprises a first lever pivotally mounted on a first pivot axis coincident with the said axis about which said squeegee is tilted, and means on said frame for adjustably supporting said first pivot axis.
 3. In a screen printing machine as claimed in claim 2 wherein said adjustable suspension means mean comprises a second lever pivotally mounted on said frame to adjust said first pivot axis substantially perpendicular to a plane tangential to the stencil in the vicinity of the contact of the stencil by the squeegee.
 4. In a screen printing machine as claimed in claim 3 wherein said first lever comprises a bell crank having first and second ends, said supporting means being connected to said first end, and an adjustable mechanism movable along a scale connected to the second end of said bell crank. 